1. 1 THE USER INTERFACE Interface Design

2. 2 Requirements for a good HCI appropriate for the level and domain of expertise good interface mechanics –menus, icons, buttons,... user-friendliness (qualities) –ease of use, consistency, robustness,... –adaptability (parameterization) –possible extendibility

3. 3 Styles of Human-Machine Interaction Command Language Menu-Driven Window-Oriented

4. 4 Command Language - Characteristics user view –application specific language –line oriented –character based, no graphics –sequential

5. 5 Command Language - Characteristics technology –hardware: “dumb” terminal –software: compiler (text parsing) oriented interpretation by virtual machine programming languages

6. 6 Menu-Driven - Characteristics user view –sequence of selections & forms –full-screen oriented (text) –hierarchical (network of screens) –predefined problem partitioning

7. 7 Menu-Driven - Characteristics technology –hardware: terminal & full keyboard –software: full-screen, layout oriented languages function keys and triggers

8. 8 Window-Oriented - Characteristics user view –desktop metaphor –set of interface primitives: windows, icons, pull-down menus, etc. –different types of windows for graphics, text, video,... –parallelism (simultaneous views)

9. 9 Window-Oriented - Characteristics technology –hardware: pointing device bit-mapped (touch-sensitive) screen –software: interface language prg. language standard libraries & object-orientedness includes a communication component, etc.

10. 10 Command Language - Discussion highly domain (application) specific must be application expert & language expert interface mechanics: primitive ease of use, consistency: language dependent parameterization: minimal extendibility: possibly high (scripts, pipes,...) well suited for advanced expert user ===> language design dominates interface design

11. 11 Menu-Driven - Discussion the concept is in principle domain independent well suited for screen / form oriented problems typically text driven interface mechanics ask for structured thinking and problem partitioning possible sequence of steps during execution is limited

12. 12 Menu-Driven - Discussion consistent and robust set of interaction primitives limited interaction primitives dictate style limited adaptability & extendibility good for a novice user; ok for occasional user: “takes you by the hand” ===> interface design identifies questions & forms

13. 13 Window-Oriented - Discussion the desktop metaphor is domain independent can be used for nearly every type of problem –different types of windows for different types of problems allows for a more dynamic handling of the HCI structure –create / terminate a window “on demand” –parameterization & extendibility are easier than with other styles

14. 14 Window-Oriented - Discussion richest set of interface mechanics: –a variety of styles can coexist work menu-driven for the beginner provide fast access to a group of windows for the average and advanced user open a command language window for the advanced expert –style is now a design problem, not a given side-effect of the interaction primitives

15. 15 Window-Oriented - Discussion many alternatives for design: –consistency of use is up to the designer –ease of use depends on a clear concept –the end-user might get buried in options but be without a clue how to get started and frustrated by ever changing concepts

16. 16 Window-Oriented - Discussion fully window-oriented user-interface design has become a domain of expertise in itself –complex set of decisions for –a wide variety of alternative solutions maintenance is tricky! good window-oriented design goes beyond computer science –involves psychological elements

17. 17 Suggestions for a Good Style stay close to your end-user’s way of thinking do not map old systems 1:1 without thinking use the power of the computer to improve for your end-user: –functionality –data organisation –user friendliness

18. 18 End of Section 5b